gdb/break-catch-throw.c

   1 /* Everything about catch/throw catchpoints, for GDB.
   2
   3    Copyright (C) 1986-2022 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "arch-utils.h"
  22 #include <ctype.h>
  23 #include "breakpoint.h"
  24 #include "gdbcmd.h"
  25 #include "inferior.h"
  26 #include "annotate.h"
  27 #include "valprint.h"
  28 #include "cli/cli-utils.h"
  29 #include "completer.h"
  30 #include "gdbsupport/gdb_obstack.h"
  31 #include "mi/mi-common.h"
  32 #include "linespec.h"
  33 #include "probe.h"
  34 #include "objfiles.h"
  35 #include "cp-abi.h"
  36 #include "gdbsupport/gdb_regex.h"
  37 #include "cp-support.h"
  38 #include "location.h"
  39 #include "cli/cli-decode.h"
  40
  41 /* Each spot where we may place an exception-related catchpoint has
  42    two names: the SDT probe point and the function name.  This
  43    structure holds both.  */
  44
  45 struct exception_names
  46 {
  47   /* The name of the probe point to try, in the form accepted by
  48      'parse_probes'.  */
  49
  50   const char *probe;
  51
  52   /* The name of the corresponding function.  */
  53
  54   const char *function;
  55 };
  56
  57 /* Names of the probe points and functions on which to break.  This is
  58    indexed by exception_event_kind.  */
  59 static const struct exception_names exception_functions[] =
  60 {
  61   { "-probe-stap libstdcxx:throw", "__cxa_throw" },
  62   { "-probe-stap libstdcxx:rethrow", "__cxa_rethrow" },
  63   { "-probe-stap libstdcxx:catch", "__cxa_begin_catch" }
  64 };
  65
  66 /* The type of an exception catchpoint.  Unlike most catchpoints, this
  67    one is implemented with code breakpoints, so it inherits struct
  68    code_breakpoint, not struct catchpoint.  */
  69
  70 struct exception_catchpoint : public code_breakpoint
  71 {
  72   exception_catchpoint (struct gdbarch *gdbarch,
  73                         bool temp, const char *cond_string_,
  74                         enum exception_event_kind kind_,
  75                         std::string &&except_rx)
  76     : code_breakpoint (gdbarch, bp_catchpoint, temp, cond_string_),
  77       kind (kind_),
  78       exception_rx (std::move (except_rx)),
  79       pattern (exception_rx.empty ()
  80                ? nullptr
  81                : new compiled_regex (exception_rx.c_str (), REG_NOSUB,
  82                                      _("invalid type-matching regexp")))
  83   {
  84     pspace = current_program_space;
  85     re_set ();
  86   }
  87
  88   void re_set () override;
  89   enum print_stop_action print_it (const bpstat *bs) const override;
  90   bool print_one (bp_location **) const override;
  91   void print_mention () const override;
  92   void print_recreate (struct ui_file *fp) const override;
  93   void print_one_detail (struct ui_out *) const override;
  94   void check_status (struct bpstat *bs) override;
  95   struct bp_location *allocate_location () override;
  96
  97   /* FIXME this is temporary - until ordinary breakpoints have been
  98      converted.  */
  99   int resources_needed (const struct bp_location *) override
 100   {
 101     return 1;
 102   }
 103
 104   /* The kind of exception catchpoint.  */
 105
 106   enum exception_event_kind kind;
 107
 108   /* If not empty, a string holding the source form of the regular
 109      expression to match against.  */
 110
 111   std::string exception_rx;
 112
 113   /* If non-NULL, a compiled regular expression which is used to
 114      determine which exceptions to stop on.  */
 115
 116   std::unique_ptr<compiled_regex> pattern;
 117 };
 118
 119 /* See breakpoint.h.  */
 120
 121 bool
 122 is_exception_catchpoint (breakpoint *bp)
 123 {
 124   return dynamic_cast<exception_catchpoint *> (bp) != nullptr;
 125 }
 126
 127 \f
 128
 129 /* A helper function that fetches exception probe arguments.  This
 130    fills in *ARG0 (if non-NULL) and *ARG1 (which must be non-NULL).
 131    It will throw an exception on any kind of failure.  */
 132
 133 static void
 134 fetch_probe_arguments (struct value **arg0, struct value **arg1)
 135 {
 136   struct frame_info *frame = get_selected_frame (_("No frame selected"));
 137   CORE_ADDR pc = get_frame_pc (frame);
 138   struct bound_probe pc_probe;
 139   unsigned n_args;
 140
 141   pc_probe = find_probe_by_pc (pc);
 142   if (pc_probe.prob == NULL)
 143     error (_("did not find exception probe (does libstdcxx have SDT probes?)"));
 144
 145   if (pc_probe.prob->get_provider () != "libstdcxx"
 146       || (pc_probe.prob->get_name () != "catch"
 147           && pc_probe.prob->get_name () != "throw"
 148           && pc_probe.prob->get_name () != "rethrow"))
 149     error (_("not stopped at a C++ exception catchpoint"));
 150
 151   n_args = pc_probe.prob->get_argument_count (get_frame_arch (frame));
 152   if (n_args < 2)
 153     error (_("C++ exception catchpoint has too few arguments"));
 154
 155   if (arg0 != NULL)
 156     *arg0 = pc_probe.prob->evaluate_argument (0, frame);
 157   *arg1 = pc_probe.prob->evaluate_argument (1, frame);
 158
 159   if ((arg0 != NULL && *arg0 == NULL) || *arg1 == NULL)
 160     error (_("error computing probe argument at c++ exception catchpoint"));
 161 }
 162
 163 \f
 164
 165 /* Implement the 'check_status' method.  */
 166
 167 void
 168 exception_catchpoint::check_status (struct bpstat *bs)
 169 {
 170   struct exception_catchpoint *self
 171     = (struct exception_catchpoint *) bs->breakpoint_at;
 172   std::string type_name;
 173
 174   this->breakpoint::check_status (bs);
 175   if (bs->stop == 0)
 176     return;
 177
 178   if (self->pattern == NULL)
 179     return;
 180
 181   const char *name = nullptr;
 182   gdb::unique_xmalloc_ptr<char> canon;
 183   try
 184     {
 185       struct value *typeinfo_arg;
 186
 187       fetch_probe_arguments (NULL, &typeinfo_arg);
 188       type_name = cplus_typename_from_type_info (typeinfo_arg);
 189
 190       canon = cp_canonicalize_string (type_name.c_str ());
 191       name = (canon != nullptr
 192               ? canon.get ()
 193               : type_name.c_str ());
 194     }
 195   catch (const gdb_exception_error &e)
 196     {
 197       exception_print (gdb_stderr, e);
 198     }
 199
 200   if (name != nullptr)
 201     {
 202       if (self->pattern->exec (name, 0, NULL, 0) != 0)
 203         bs->stop = 0;
 204     }
 205 }
 206
 207 /* Implement the 're_set' method.  */
 208
 209 void
 210 exception_catchpoint::re_set ()
 211 {
 212   std::vector<symtab_and_line> sals;
 213   struct program_space *filter_pspace = current_program_space;
 214
 215   /* We first try to use the probe interface.  */
 216   try
 217     {
 218       location_spec_up locspec
 219         = new_probe_location_spec (exception_functions[kind].probe);
 220       sals = parse_probes (locspec.get (), filter_pspace, NULL);
 221     }
 222   catch (const gdb_exception_error &e)
 223     {
 224       /* Using the probe interface failed.  Let's fallback to the normal
 225          catchpoint mode.  */
 226       try
 227         {
 228           location_spec_up locspec
 229             = (new_explicit_location_spec_function
 230                (exception_functions[kind].function));
 231           sals = this->decode_location_spec (locspec.get (), filter_pspace);
 232         }
 233       catch (const gdb_exception_error &ex)
 234         {
 235           /* NOT_FOUND_ERROR just means the breakpoint will be
 236              pending, so let it through.  */
 237           if (ex.error != NOT_FOUND_ERROR)
 238             throw;
 239         }
 240     }
 241
 242   update_breakpoint_locations (this, filter_pspace, sals, {});
 243 }
 244
 245 enum print_stop_action
 246 exception_catchpoint::print_it (const bpstat *bs) const
 247 {
 248   struct ui_out *uiout = current_uiout;
 249   int bp_temp;
 250
 251   annotate_catchpoint (number);
 252   maybe_print_thread_hit_breakpoint (uiout);
 253
 254   bp_temp = disposition == disp_del;
 255   uiout->text (bp_temp ? "Temporary catchpoint "
 256                        : "Catchpoint ");
 257   uiout->field_signed ("bkptno", number);
 258   uiout->text ((kind == EX_EVENT_THROW ? " (exception thrown), "
 259                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 260                    : " (exception rethrown), ")));
 261   if (uiout->is_mi_like_p ())
 262     {
 263       uiout->field_string ("reason",
 264                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 265       uiout->field_string ("disp", bpdisp_text (disposition));
 266     }
 267   return PRINT_SRC_AND_LOC;
 268 }
 269
 270 bool
 271 exception_catchpoint::print_one (bp_location **last_loc) const
 272 {
 273   struct value_print_options opts;
 274   struct ui_out *uiout = current_uiout;
 275
 276   get_user_print_options (&opts);
 277
 278   if (opts.addressprint)
 279     uiout->field_skip ("addr");
 280   annotate_field (5);
 281
 282   switch (kind)
 283     {
 284     case EX_EVENT_THROW:
 285       uiout->field_string ("what", "exception throw");
 286       if (uiout->is_mi_like_p ())
 287         uiout->field_string ("catch-type", "throw");
 288       break;
 289
 290     case EX_EVENT_RETHROW:
 291       uiout->field_string ("what", "exception rethrow");
 292       if (uiout->is_mi_like_p ())
 293         uiout->field_string ("catch-type", "rethrow");
 294       break;
 295
 296     case EX_EVENT_CATCH:
 297       uiout->field_string ("what", "exception catch");
 298       if (uiout->is_mi_like_p ())
 299         uiout->field_string ("catch-type", "catch");
 300       break;
 301     }
 302
 303   return true;
 304 }
 305
 306 /* Implement the 'print_one_detail' method.  */
 307
 308 void
 309 exception_catchpoint::print_one_detail (struct ui_out *uiout) const
 310 {
 311   if (!exception_rx.empty ())
 312     {
 313       uiout->text (_("\tmatching: "));
 314       uiout->field_string ("regexp", exception_rx);
 315       uiout->text ("\n");
 316     }
 317 }
 318
 319 void
 320 exception_catchpoint::print_mention () const
 321 {
 322   struct ui_out *uiout = current_uiout;
 323   int bp_temp;
 324
 325   bp_temp = disposition == disp_del;
 326   uiout->message ("%s %d %s",
 327                   (bp_temp ? _("Temporary catchpoint ") : _("Catchpoint")),
 328                   number,
 329                   (kind == EX_EVENT_THROW
 330                    ? _("(throw)") : (kind == EX_EVENT_CATCH
 331                                      ? _("(catch)") : _("(rethrow)"))));
 332 }
 333
 334 /* Implement the "print_recreate" method for throw and catch
 335    catchpoints.  */
 336
 337 void
 338 exception_catchpoint::print_recreate (struct ui_file *fp) const
 339 {
 340   int bp_temp;
 341
 342   bp_temp = disposition == disp_del;
 343   gdb_printf (fp, bp_temp ? "tcatch " : "catch ");
 344   switch (kind)
 345     {
 346     case EX_EVENT_THROW:
 347       gdb_printf (fp, "throw");
 348       break;
 349     case EX_EVENT_CATCH:
 350       gdb_printf (fp, "catch");
 351       break;
 352     case EX_EVENT_RETHROW:
 353       gdb_printf (fp, "rethrow");
 354       break;
 355     }
 356   print_recreate_thread (fp);
 357 }
 358
 359 /* Implement the "allocate_location" method for throw and catch
 360    catchpoints.  */
 361
 362 bp_location *
 363 exception_catchpoint::allocate_location ()
 364 {
 365   return new bp_location (this, bp_loc_software_breakpoint);
 366 }
 367
 368 static void
 369 handle_gnu_v3_exceptions (int tempflag, std::string &&except_rx,
 370                           const char *cond_string,
 371                           enum exception_event_kind ex_event, int from_tty)
 372 {
 373   struct gdbarch *gdbarch = get_current_arch ();
 374
 375   std::unique_ptr<exception_catchpoint> cp
 376     (new exception_catchpoint (gdbarch, tempflag, cond_string,
 377                                ex_event, std::move (except_rx)));
 378
 379   install_breakpoint (0, std::move (cp), 1);
 380 }
 381
 382 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 383    by whitespace.
 384
 385    If there is any non-whitespace text between *STRING and the "if"
 386    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 387    this returns NULL.
 388
 389    STRING is updated to point to the "if" token, if it exists, or to
 390    the end of the string.  */
 391
 392 static std::string
 393 extract_exception_regexp (const char **string)
 394 {
 395   const char *start;
 396   const char *last, *last_space;
 397
 398   start = skip_spaces (*string);
 399
 400   last = start;
 401   last_space = start;
 402   while (*last != '\0')
 403     {
 404       const char *if_token = last;
 405
 406       /* Check for the "if".  */
 407       if (check_for_argument (&if_token, "if", 2))
 408         break;
 409
 410       /* No "if" token here.  Skip to the next word start.  */
 411       last_space = skip_to_space (last);
 412       last = skip_spaces (last_space);
 413     }
 414
 415   *string = last;
 416   if (last_space > start)
 417     return std::string (start, last_space - start);
 418   return std::string ();
 419 }
 420
 421 /* See breakpoint.h.  */
 422
 423 void
 424 catch_exception_event (enum exception_event_kind ex_event,
 425                        const char *arg, bool tempflag, int from_tty)
 426 {
 427   const char *cond_string = NULL;
 428
 429   if (!arg)
 430     arg = "";
 431   arg = skip_spaces (arg);
 432
 433   std::string except_rx = extract_exception_regexp (&arg);
 434
 435   cond_string = ep_parse_optional_if_clause (&arg);
 436
 437   if ((*arg != '\0') && !isspace (*arg))
 438     error (_("Junk at end of arguments."));
 439
 440   if (ex_event != EX_EVENT_THROW
 441       && ex_event != EX_EVENT_CATCH
 442       && ex_event != EX_EVENT_RETHROW)
 443     error (_("Unsupported or unknown exception event; cannot catch it"));
 444
 445   handle_gnu_v3_exceptions (tempflag, std::move (except_rx), cond_string,
 446                             ex_event, from_tty);
 447 }
 448
 449 /* Implementation of "catch catch" command.  */
 450
 451 static void
 452 catch_catch_command (const char *arg, int from_tty,
 453                      struct cmd_list_element *command)
 454 {
 455   bool tempflag = command->context () == CATCH_TEMPORARY;
 456
 457   catch_exception_event (EX_EVENT_CATCH, arg, tempflag, from_tty);
 458 }
 459
 460 /* Implementation of "catch throw" command.  */
 461
 462 static void
 463 catch_throw_command (const char *arg, int from_tty,
 464                      struct cmd_list_element *command)
 465 {
 466   bool tempflag = command->context () == CATCH_TEMPORARY;
 467
 468   catch_exception_event (EX_EVENT_THROW, arg, tempflag, from_tty);
 469 }
 470
 471 /* Implementation of "catch rethrow" command.  */
 472
 473 static void
 474 catch_rethrow_command (const char *arg, int from_tty,
 475                        struct cmd_list_element *command)
 476 {
 477   bool tempflag = command->context () == CATCH_TEMPORARY;
 478
 479   catch_exception_event (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 480 }
 481
 482 \f
 483
 484 /* Implement the 'make_value' method for the $_exception
 485    internalvar.  */
 486
 487 static struct value *
 488 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 489 {
 490   struct value *arg0, *arg1;
 491   struct type *obj_type;
 492
 493   fetch_probe_arguments (&arg0, &arg1);
 494
 495   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 496      the std::type_info for the exception.  Now we find the type from
 497      the type_info and cast the result.  */
 498   obj_type = cplus_type_from_type_info (arg1);
 499   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 500 }
 501
 502 /* Implementation of the '$_exception' variable.  */
 503
 504 static const struct internalvar_funcs exception_funcs =
 505 {
 506   compute_exception,
 507   NULL,
 508 };
 509
 510 \f
 511
 512 void _initialize_break_catch_throw ();
 513 void
 514 _initialize_break_catch_throw ()
 515 {
 516   /* Add catch and tcatch sub-commands.  */
 517   add_catch_command ("catch", _("\
 518 Catch an exception, when caught."),
 519                      catch_catch_command,
 520                      NULL,
 521                      CATCH_PERMANENT,
 522                      CATCH_TEMPORARY);
 523   add_catch_command ("throw", _("\
 524 Catch an exception, when thrown."),
 525                      catch_throw_command,
 526                      NULL,
 527                      CATCH_PERMANENT,
 528                      CATCH_TEMPORARY);
 529   add_catch_command ("rethrow", _("\
 530 Catch an exception, when rethrown."),
 531                      catch_rethrow_command,
 532                      NULL,
 533                      CATCH_PERMANENT,
 534                      CATCH_TEMPORARY);
 535
 536   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 537 }